What’s In a Camshaft?

Dec 2, 2009

The camshaft is often referred to as the heart of an engine or the brains behind the whole intake, compression, combustion and exhaust process.

While most people will never think to replace their vehicle’s camshaft, those that do are definite enthusiasts, working with racecars, hot rods or both.

When these dedicated customers ask why one camshaft costs more than another or why an aftermarket camshaft is needed at all, it’s only fair to have some solid answers to the question, what’s in a camshaft?
Four prominent camshaft manufacturers give us their answers in this article, as well as their views on a few issues facing the performance aftermarket for camshafts.

Camshaft Quality

In discussing what elements make for a performance camshaft, there are a great number of factors to consider.

According to Chris Douglas of Comp Cams in Memphis, Tenn., many of these factors deal with grinding and material (surface finish, profile accuracy, run out, taper, chatter, material cleanliness, hardness and chemical composition, etc).

“Truly, we could list these attributes for days! However, no matter how well you execute the grinding side, if the design is not the best, then your engine is not going to perform. Choosing a well-made camshaft, from a reputable company, with a modern design that gets the valve on and off the seat as quickly as possible and has the right duration and lobe angles to perform in the given application is what matters,” he says.

John Steely, sales manager for Howards Cams in Oshkosh, Wis., says it all starts with the core, adding that there are only so many top core manufacturers in the U.S. Most of the name-brand cam companies get the core for their cams from these manufacturers, he says.

After the core, Steely looks at the machining of the cam. The cam lobes must be ground with the correct ramps and taper for the application to make sure the lifter will rotate correctly.

“These factors can greatly affect the life and performance of the camshaft. But let me also say, that without the proper ‘break-in’ procedure and lubricants, that the quality of the cam will not matter; you will have problems,” says Steely.

Dave Crower of Crower Cams in San Diego says application and spring pressure also play a vital role.

“Now, whether that’s a flat tappet cam or a hydraulic cam or a hydraulic roller or whatever the combination is, the quality would definitely show up as the type of cam, the type of application and the type of spring pressure being used. That’s because there are four types of material, depending on what combination and application you’re talking about,” he says.

Derek Scott of Lunati Cams in Olive Branch, Miss., says, “I think the first important thing is to ask what kind of customer service are you going to get if you run into any issues? There are a bunch of different things that help out on the quality of a camshaft. The feeds and speeds of the grinder that you use, the actual coolant that you use, where you’re spraying it and making sure you don’t use too much. A lot of that is going to determine the quality of the finish you get on the camshaft, and also the equipment plays a major factor. We’ve got a Landis CNC machine that we really like to brag about, and we use a CBN grinding wheel, and it gives a real consistent profile from lobe to lobe.”

He adds that the quality of a camshaft is mostly determined by the quality of the craftsmanship used to make it.

Types of Camshafts

Generally speaking, that craftsmanship is used to create four types of camshafts, says Steely.

“Howards Cams grinds hydraulic flat tappet, hydraulic roller, solid flat tappet and solid roller cams. Applications range from mild street performance to Top Fuel, circle track, marine performance and race, puller and tractor, antique, air boat and even stationary engines.”

However, for each type of camshaft, there are practically an unlimited number of options available. Douglas notes that Comp Cams has more than 10,000 profiles to choose from, along with several hundred cores in the four major categories of camshafts. Again, those are hydraulic roller, solid roller, hydraulic flat tappet and solid flat tappet.

Crower notes that of the hydraulic flat tappet and the hydraulic rollers, the latter tend to be more desirable.

“Those have friction savings, fuel economy, faster lift rates, more horsepower and other particulars for a hydraulic roller. The hydraulic flat tappet and hydraulic roller are both a little limited with rpm; 6,500 is the redline because you can’t run enough spring pressure for elevated rpm (however, with custom work, this can be achieved). Then, you get into flat tappet stuff, and you’ve got flat tappet solid lifter profiles, and mostly those are for higher rpm applications.”

He adds that for a street engine or a limited-rpm engine, he recommends a hydraulic flat tappet or hydraulic roller camshaft. “They’re virtually trouble-free as no valve adjustment is required,” says Crower.

Scott says that generally, flat tappets are used for racing and for older vehicles. “The older OE cams were flat tappet style, and a lot of your dirt track and oval track guys run flat tappets still. They have rules that require flat tappets.”

He adds that the roller class guys’ cams are made from steel billets. “Today, all of the new engines come with hydraulic rollers. We’ve got a couple of different selections for that side. We’ve got what we call SADI (Selectively Austempered Ductile Iron) core, and we also offer the billet style for the hydraulic roller guys. The SADI core works on most street applications. It’s an iron core versus a billet core, but for any high-end race applications, you definitely need to go with the billet style core.”

Materials Make a Difference

When making a camshaft, the materials make a difference, but not necessarily in the same manner as other internal engine hard parts. Rather than seeking the strongest and most durable material, proper cam construction is based on individual applications and how it will complement the overall engine setup.

Most manufacturers use approximately the same types of steel, but we let them address specifically what they offer.

“On flat tappet grinds, we typically use cast iron, of which there are two different grades. Most are flame-hardened, but we also offer nitrided camshafts,” says Douglas. “On overheads, there are many choices in sliding applications, but chilled iron is the most common. On roller cams, the standard steels are SAE 5160 induction-hardened, SAE 5160 QT + IH, SAE 8620 copper-masked, carburized and QT, SAE 9310 copper coat, carburized and QT with a triple-temper that includes a cryogenic step, SAE 1079, SAE 8650, a proprietary tool steel alloy and SADI iron. These are all used commonly. We also have a few dozen other specialty alloys used in various applications. The proprietary tool steel alloy is used in all NASCAR flat tappet cams.”

Steely notes that some of the materials his company uses are cast Pro 55, Proferall, 8620 Steel, 8660 Steel, 5150 Steel and SADI.

Crower says his company uses the conventional cast material.

“Most of it is modular material. It’s a cast material, and then you get into the Pro 55 material, which has more carbide and is harder. We use that for the performance cams, and that would represent flat tappet or hydraulic flat tappet for small-block and big-block Chevy engines. Then, you get into your different types of steel billet for hydraulic rollers and mechanical rollers. You’ve got a cast roller cam for small blocks and big blocks, which you can normally get away with because of the lighter spring pressures and rpm requirements. When you get into more of the race stuff in hydraulic, we have an 8620 steel billet material that we use. The next choice would be a race flat tappet, and we have flat tappets that are made of tool-steel material that are hard all the way through that require no hard facing, but they’re very expensive, and again, they’re all custom ordered.”

Scott notes 99.9 percent of flat tappets, unless it’s NASCAR Sprint Cup, will be cast material.

“We do have some of what we call Pro55 cast core that are a Rockwell 55, and it’s just a tougher cast core. You definitely want to use that when you’re racing, but it’s not really necessary for street guys or guys who just want a little extra torque,” he says, adding, “we have a 5160 material, 8650, 8620, etc. Those would be used in roller applications. We’ve got a real broad range, and probably for 99 percent of your customer base out there, any of those will work fine.”

Differences from Stock

The most significant difference between aftermarket camshafts and stock camshafts is that an aftermarket camshaft is designed for specific applications. That, more than the material used or method utilized to create the camshaft, is what a customer pays for when purchasing an aftermarket camshaft. It’s all about the profile.

All the same, Steely explains, “performance cams are typically made from more durable materials and with more aggressive lobe designs to increase the cylinder pressure and thus power output.”

Yet, with camshafts, the true performance advantages come from fine tuning. Small adjustments can make a big difference.

“In a recent test,” explains Douglas, “we took a new L92 engine and tested it with the stock setup except we modified the air box to fit our dyno air and we added headers. The stock power figures are 400-hp SAE. We measured 430 hp with those very slight modifications.”

He adds, “By swapping to our largest cam and phase limiter setup, we were able to increase power to 500-hp SAE on the average of three runs. When we design a camshaft, we are not confined by the same limitations or restrictions as the OEMs. The result is we are able to produce camshafts (valve train system combinations) that produce much greater performance and are more tailored to specific applications, rpm ranges, etc.”

Addressing Douglas’ point about the OEMs, Crower says, “Typically, the OE factories with their R&D departments are capable of the stuff we do performance-wise, but the average car buyer does not want to run high rpms, a supercharger or give up low-speed torque to have bigger duration.”

Again, Crower says the main difference between aftermarket camshafts and those from the OEM are that aftermarket cams are made for more specific racing or hot rod applications. They offer end-users more flexibility to get precisely what they want for their specific engine.

“That’s the neat thing we can do,” says Scott. “We can tailor each person’s camshaft to their individual build. That’s why you replace a cam: you’re putting other components on there, and you want to match everything up. You don’t want to leave the camshaft at stock specs, because it’s not going to be compatible with everything else.”

However, he adds that they also offer cams that you can run with OE components if you just want to boost a little power by changing the cam. They also do quite a bit of custom work.

Choosing the Correct Camshaft

If an aftermarket camshaft is all about finding something tuned for a specific setup, how do enthusiasts know they’re ordering the correct camshaft for their racecar or hot rod?

“The best cam choices can be made with the most detailed information on the entire combination, such as engine specifics, vehicle details and intended usage,” says Steely.

In almost all cases, Douglas recommends that a person contact someone they trust at the manufacturing company when selecting a camshaft, noting his company offers a toll-free tech support line. He says the cam is often called the “heart” or “mind” of a performance engine; it needs to be tailored around that particular build.

Yet he is quick to point out that Comp Cams is in no way saying that everyone needs a custom grind. In fact, “We put just as much development into our ‘shelf’ grinds as we do into a custom piece. However, you need to discuss what you are trying to accomplish with an expert. They can help you select the best choice from our current grinds, if yours is similar to what we had in mind when we formed that particular series. If not, we will steer you toward whatever custom grind you need.”

Douglas adds there are also some very advanced computer simulation programs such as CamQuest 6 and Dyno Sim that can be a great tool to point you in a general direction on camshaft design.

Crower says that choosing the correct camshaft all depends on the rpms and the rpm requirements.

“It’s all about the application,” says Crower. “We do a lot of custom cams, and the data that we require from the customer is cylinder head data, cylinder head flow. What is the valve size? What is the bore stroke and rod length? This is all the typical stuff that you need to develop a camshaft.”

Scott concurs. “Any customer would call our tech line, and give the tech their specific information: the cylinder head, block, stroke, bore, carburetor, intake, rocker ratio-the whole nine yards. We’ll take that information and select an intake lobe, an exhaust lobe and figure out what lobe separation is going to work best for that particular setup.”

Final Rotation

Camshaft manufacturers are currently facing challenges that all other aspects of the aftermarket have come to feel as well.

Crower mentions that though the cost of fuel has recently come down, most agree that it’s only a matter of time before it goes back up again. Every extra dollar enthusiasts pay just to fill up their tanks is one less dollar they can spend on performance items, he says.

Despite the current economic climate, those who know more sell more, and educating yourself, and developing a strong relationship with your camshaft manufacturer, will only help your sales and your company.

OIL INFLUENCES

Another factor that contributes to camshaft performance is oil. The lubricity of oil has been a recent issue for nearly all manufacturers of internal engine components.

“Motor oil has changed over the years, mainly with the removal of zinc-phosphates (ZDDP). The reason for the removal is because today’s new cars have roller tappet camshafts. Roller tappet cams do not require these additives that flat tappet (hydraulic or mechanical) camshafts need. Flat tappet camshafts require this extra protection because the lifter slides across the cam lobe. This metal-to-metal contact between the cam and lifter will not last long without this additive, especially during ‘break-in,'” says John Steely, sales manager for Howards Cams.

There are specialty oil manufactures, such as Brad Penn, that have this additive, he notes. But most of the common name brands (including Shell Rotella) no longer have zinc-phosphates at all.

“We have blended an additive that has the highest levels of zinc-phosphates (ZDDP) per volume that we can find. We also have added molybdenum for added protection. One 4-ounce bottle is enough for up to six quarts of oil. Some have bigger bottles, but most only have more mineral oil,” says Steely.

Chris Douglas says Comp Cams has also had more issues with the lower ZDDP content of motor oils due to EPA constraints dealing with catalytic converter life. For a while, they tried moving people toward diesel oils like Rotella. However, even those have had to lower the anti-wear additive levels. This is mostly an issue on flat tappet cam applications with premature wear.

“Now,” Douglas adds, “we recommend the use of our #159 Engine Break-In Oil Additive to offset this loss. Typically one bottle for every four to five quarts for break-in and half that much with every oil change dramatically helps the issue.”

His company also recommends its nitriding service. That’s a service that Lunati offers as well.

“It’s for flat tappets and cast pieces, but it’s a surface enhancement-it’s not a coating-that brings up the surface hardness of the flat tappets. Especially in today’s world, with the flat tappets and the oils having less lubricity, the nitriding process greatly reduces your chances of failure and a flat tappet bearing breaking. It really strengthens the core and the surface hardness,” says Derek Scott of Lunati.